I struggled to find a fanfic to post here. I don't write them myself and most of the ones I read I wouldn't admit to reading. I eventually picked on that I definitely didn't think I would like.
Crossovers are not something I typically read, they are usually poorly written and contrived. However this one I genuinely like. The story is call "We shouldn't keep meeting like this" and it crosses over two of my favorite Sci-fi shows, Doctor Who and Stargate SG-1. What I love about it is that the two characters never really find out a lot about each other and the complexity of time travel confuses there stories, as one is living the "slow life" and the other is hopping through time. The first time they meet for one is actually the last time they meet for the other. Jack and Jack definitely have personalities that can clash, but also they get along quite well at times.
If you haven't watched either show then it will all go right over your head, but if you've watched the shows it's a great read.